CN109083757B - Engine dual-fuel proportion control method and device and automobile - Google Patents
Engine dual-fuel proportion control method and device and automobile Download PDFInfo
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- CN109083757B CN109083757B CN201810947522.0A CN201810947522A CN109083757B CN 109083757 B CN109083757 B CN 109083757B CN 201810947522 A CN201810947522 A CN 201810947522A CN 109083757 B CN109083757 B CN 109083757B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/30—Controlling fuel injection
- F02D41/3094—Controlling fuel injection the fuel injection being effected by at least two different injectors, e.g. one in the intake manifold and one in the cylinder
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/08—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels
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Abstract
The invention discloses a method and a device for controlling the dual-fuel proportion of an engine and an automobile, wherein the control method comprises the following steps: if the engine is in a rapid acceleration state, calculating a first demand quantity of a first fuel and a second demand quantity of a second fuel at a first position before the top dead center of each cylinder, and controlling a first fuel injection device to inject the first fuel to each cylinder according to the calculated first demand quantity; and calculating a third demand of a second fuel at a second position before the top dead center of each cylinder, updating the second demand of the second fuel according to the third demand, and controlling a second fuel injection device to inject the second fuel to each cylinder according to the third demand, so that when the first fuel injection has lag and the first fuel actually injected into the cylinder is too little, the problem of insufficient vehicle power caused by methanol injection lag under the condition of sudden acceleration of the vehicle is avoided by increasing the injection amount of the second fuel and adjusting the proportion of two fuels entering the engine cylinder.
Description
Technical Field
The embodiment of the invention relates to an engine control technology, in particular to a method and a device for controlling the dual-fuel proportion of an engine and an automobile.
Background
Natural gas and methanol fuels have the advantages of high economy, good emission and the like, so that the application of the dual-fuel engine which jointly uses the traditional diesel fuel and the natural gas or the methanol fuel is more and more extensive.
For the methanol diesel dual-fuel engine, the diesel fuel is directly sprayed into each cylinder through a fuel injector; methanol fuel is typically stored in a methanol tank, passed through an intake manifold and an intake manifold, and ultimately injected into the various cylinders of the engine. In the prior art, when the vehicle has a transient condition of sudden acceleration or sudden deceleration, the injection amount of methanol is usually increased by increasing or decreasing the injection time period of methanol.
However, methanol injected into the cylinder is delayed due to the long gas path, and if the accelerator pedal is suddenly increased, the fuel entering the cylinder is slightly less due to the delayed methanol injection, so that the problem of insufficient power is caused.
Disclosure of Invention
The invention provides an engine dual-fuel proportion control method, an engine dual-fuel proportion control device and an automobile, which are used for accurately controlling the proportion of two fuels entering each cylinder of an engine and avoiding the problem of insufficient vehicle power caused by less fuel entering the cylinder due to the delay of methanol injection in the sudden acceleration working condition of the vehicle.
In a first aspect, an embodiment of the present invention provides a dual-fuel proportion control method for an engine, where the engine includes a first fuel injection device, a second fuel injection device, and a plurality of cylinders that sequentially cycle to do work according to a set order, and the dual-fuel proportion control method for the engine includes:
if the engine is in a rapid acceleration state, calculating a first demand quantity of a first fuel and a second demand quantity of a second fuel at a first position before the top dead center of each cylinder, and controlling a first fuel injection device to inject the first fuel to each cylinder according to the calculated first demand quantity;
calculating a third demand of the second fuel at a second position before the top dead center of each cylinder, updating the second demand of the second fuel according to the third demand, and controlling the second fuel injection device to inject the second fuel into each cylinder according to the third demand;
wherein, for any cylinder, at the first position before top dead center, neither the first fuel injection means nor the second fuel injection means injects fuel into the cylinder; when the first fuel injection device finishes injecting the first fuel to the cylinder, the second fuel injection device does not inject the second fuel to the cylinder.
Wherein, before judging that the engine is in the rapid acceleration state, include:
detecting at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the oil quantity required by the torque of the engine in real time;
and judging the working condition of the engine according to at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the oil quantity required by the torque of the engine.
When the engine speed change rate is larger than a first speed change rate threshold value, or the accelerator pedal opening change rate is larger than a first accelerator opening change rate threshold value, or the engine torque demand oil quantity change rate is larger than a first demand oil quantity change rate threshold value, the engine is judged to be in a rapid acceleration state.
When the engine rotating speed change rate is smaller than or equal to a second rotating speed change rate threshold value, or the accelerator pedal opening change rate is smaller than or equal to a second accelerator opening change rate threshold value, or the engine torque demand oil quantity change rate is smaller than or equal to a second demand oil quantity change rate threshold value, the engine is judged to be in a rapid deceleration state; the engine dual-fuel proportion control method further comprises the following steps:
and if the engine is judged to be in a rapid deceleration state, controlling the first fuel injection device to stop injecting the first fuel, wherein the second fuel demand of each cylinder is equal to the total fuel demand of the cylinder.
When the engine rotating speed change rate is greater than a second rotating speed change rate threshold and is less than or equal to a first rotating speed change rate threshold, or the accelerator pedal opening change rate is greater than a second accelerator opening change rate threshold and is less than or equal to a first accelerator opening change rate threshold, or the engine torque required oil quantity change rate is greater than a second required oil quantity change rate threshold and is less than or equal to a first required oil quantity change rate threshold, the engine is judged to be in a steady-state working condition; the engine dual-fuel proportion control method further comprises the steps of controlling the first fuel injection device to inject the first fuel to each cylinder according to the first demand quantity of the first fuel and controlling the second fuel injection device to inject the second fuel to each cylinder according to the second demand quantity of the second fuel when the engine is in a steady-state working condition.
Wherein calculating a third demand for the second fuel at a second location before top dead center of each cylinder comprises:
calculating the total demand of the second fuel of each cylinder in real time according to the engine torque at the second position before the top dead center of the cylinder;
equivalently converting a first fuel actually injected into the cylinder by the first fuel injection means into a second fuel amount in accordance with a calorific value;
and determining the difference between the total required quantity of the second fuel of the cylinder and the quantity of the second fuel obtained by the equivalent conversion of the first fuel as a third required quantity of the second fuel of the cylinder.
The engine comprises six cylinders, and the first position before the top dead center is 138 degrees before the top dead center, and the second position before the top dead center is 78 degrees before the top dead center.
Wherein the first fuel is methanol and the second fuel is diesel.
In a second aspect, an embodiment of the present invention further provides a dual-fuel proportional control device for an engine, where the engine includes a first fuel injection device, a second fuel injection device, and a plurality of cylinders that sequentially and cyclically do work according to a set order, and the dual-fuel proportional control device for the engine includes:
the first calculation control module is used for calculating a first demand of a first fuel and a second demand of a second fuel at a first position before the top dead center of each cylinder if the engine is in a rapid acceleration state, and controlling the first fuel injection device to inject the first fuel to each cylinder according to the calculated first demand;
the updating control module is used for calculating a third demand of the second fuel at a second position before the top dead center of each cylinder, updating the second demand of the second fuel according to the third demand and controlling the second fuel injection device to inject the second fuel to each cylinder according to the third demand;
wherein, for any cylinder, at the first position before top dead center, neither the first fuel injection means nor the second fuel injection means injects fuel into the cylinder; when the first fuel injection device finishes injecting the first fuel to the cylinder, the second fuel injection device does not inject the second fuel to the cylinder.
Wherein, the dual fuel proportional control device of engine still includes engine operating mode judgement module, and engine operating mode judgement module includes:
the detection unit is used for detecting at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the torque required oil quantity of the engine in real time;
and the judging unit is used for judging the working condition of the engine according to at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the oil quantity required by the torque of the engine.
The judgment unit comprises a rapid acceleration state judgment subunit, and the rapid acceleration state judgment subunit is used for judging that the engine is in a rapid acceleration state when the engine rotating speed change rate is greater than a first rotating speed change rate threshold, or the accelerator pedal opening change rate is greater than a first accelerator opening change rate threshold, or the engine torque demand oil volume change rate is greater than a first demand oil volume change rate threshold.
The judgment unit further comprises a rapid deceleration state judgment subunit, wherein the rapid deceleration state judgment subunit is used for judging that the engine is in a rapid deceleration state when the change rate of the engine rotating speed is smaller than or equal to a second rotating speed change rate threshold, or the change rate of the accelerator pedal opening is smaller than or equal to a second accelerator opening change rate threshold, or the change rate of the engine torque oil demand is smaller than or equal to a second oil demand change rate threshold;
the engine dual-fuel proportional control device comprises a second control module and a second control module, wherein the second control module is used for controlling the first fuel injection device to stop injecting the first fuel if the engine is determined to be in a rapid deceleration state, and the second fuel demand of each cylinder is equal to the total fuel demand of the cylinder.
The judging unit further comprises a steady-state working condition judging subunit, wherein the steady-state working condition judging subunit is used for judging that the engine is in a steady-state working condition when the engine rotating speed change rate is larger than a second rotating speed change rate threshold and is smaller than or equal to a first rotating speed change rate threshold, or the accelerator pedal opening change rate is larger than a second accelerator opening change rate threshold and is smaller than or equal to a first accelerator opening change rate threshold, or the engine torque required oil quantity change rate is larger than a second required oil quantity change rate threshold and is smaller than or equal to a first required oil quantity change rate threshold;
the engine dual-fuel proportional control device further comprises a third control module, wherein the third control module is used for controlling the first fuel injection device to inject the first fuel to each cylinder according to the first demand quantity of the first fuel and controlling the second fuel injection device to inject the second fuel to each cylinder according to the second demand quantity of the second fuel when the engine is in a steady-state working condition.
The updating control module comprises a second fuel total demand calculation unit, an equivalent conversion unit and a third demand calculation unit;
the total fuel demand calculation unit is used for calculating the total demand of the second fuel of each cylinder in real time according to the engine torque at a second position before the top dead center of the cylinder;
the equivalent conversion unit is used for converting the first fuel actually injected into the cylinder by the first fuel injection device into a second fuel amount in an equivalent manner according to the heat value;
the third demand calculation unit is configured to determine a difference between the total demand of the second fuel for the cylinder and the amount of the second fuel equivalently converted from the first fuel as the third demand of the second fuel for the cylinder.
In a third aspect, the embodiment of the invention also provides an automobile, which comprises an engine and an engine electronic control unit, wherein the engine dual-fuel proportional control device provided by the second aspect is integrated in the engine electronic control unit.
The invention calculates a first demand quantity of a first fuel and a second demand quantity of a second fuel at a first position before top dead center of each cylinder when the first fuel injection device and the second fuel injection device do not inject the first fuel and the second fuel to the cylinder when the engine is judged to be in a rapid acceleration state, and controls the first fuel injection device to inject the first fuel to the cylinder according to the first fuel demand quantity; and calculating a third required amount of the second fuel at a second position before top dead center of each cylinder where the second fuel is not injected into the cylinder by the second fuel injection means after injection of the first fuel into the cylinder by the first fuel injection means is completed, and updating the second required amount with the third required amount, and then controls the second fuel injection means to inject the second fuel to each cylinder in accordance with the third required amount, therefore, when the vehicle is in a rapid acceleration working condition, after the first fuel injection of each cylinder is finished, the injection amount of the second fuel is adjusted in accordance with the amount of the first fuel actually injected into the cylinder, so that when there is a delay in the injection of the first fuel and the amount of the first fuel actually injected into the cylinder is too small, by increasing the injection quantity of the second fuel and adjusting the proportion of the two fuels entering the cylinder of the engine, the problem of insufficient vehicle power caused by less fuel entering the cylinder due to the injection delay of methanol under the condition of sudden acceleration of the vehicle is avoided.
Drawings
Fig. 1 is a flowchart of a method for controlling a dual fuel ratio of an engine according to an embodiment of the present invention.
Fig. 2 is a flowchart of a method for controlling the dual fuel ratio of the engine according to a second embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a dual-fuel proportional control device of an engine according to a third embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a dual-fuel proportional control device of an engine according to a fourth embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 1 is a flowchart of a dual fuel proportion control method for an engine according to an embodiment of the present invention, where the control method can be executed by a dual fuel proportion control device for an engine, the engine includes a first fuel injection device, a second fuel injection device, and a plurality of cylinders that sequentially cycle to do work according to a set order, and the dual fuel proportion control method for an engine includes:
specifically, the engine of the vehicle generally includes a plurality of cylinders, and when the vehicle is in operation, the plurality of cylinders sequentially apply work according to a preset sequence and cyclically reciprocate. For dual fuel automotive engines, when the path taken by a fuel to enter an engine cylinder is long, there is hysteresis in the fuel injected into the cylinder. For example, methanol fuel is usually stored in a methanol tank and is finally injected into each cylinder of an engine through an intake manifold and an intake manifold, the gas path is long, and the injection of the methanol is delayed, which is reflected in the problem that when a vehicle is in a rapid acceleration state, the methanol cannot be timely injected into the cylinder, so that the fuel entering the cylinder is little and the power is insufficient.
Based on the above problems, the present embodiment provides the above engine dual fuel ratio control method to avoid the problem of insufficient vehicle power due to the lag of a certain fuel entering the cylinder. Specifically, for any cylinder, a first demand amount of a first fuel and a second demand amount of a second fuel are calculated at a first position before top dead center of each cylinder respectively in a cycle period in which each cylinder sequentially performs work. Wherein, for any cylinder, at the first position before the top dead center, the first fuel injection device and the second fuel injection device do not inject fuel to the cylinder in the current period. That is, when two kinds of fuel are not injected into a certain cylinder in one cycle period, a first required amount of the first fuel and a second required amount of the second fuel are calculated, and then the first fuel injection device is controlled to inject the first fuel into the corresponding cylinder according to the calculated first required amount of the first fuel. Alternatively, the first fuel is a fuel having a longer path from the cylinder. Due to the long path that the first fuel needs to travel to enter the cylinder, the amount of the first fuel actually injected into the cylinder may be less than the calculated first demand during a rapid acceleration of the vehicle.
And step 120, calculating a third demand of the second fuel at a second position before the top dead center of each cylinder, updating the second demand of the second fuel according to the third demand, and controlling the second fuel injection device to inject the second fuel to each cylinder according to the third demand.
In order to avoid the problem of power shortage caused by the fact that the first fuel quantity actually injected into the cylinder is smaller than the calculated first fuel demand when the vehicle is accelerated suddenly, and the total fuel in the cylinder is too little, the demand quantity of the second fuel, namely the third demand quantity, is recalculated at the second position before the top dead center of each cylinder. And when the second position is reached, the first fuel injection device finishes injecting the first fuel to the cylinder, and the second fuel injection device does not inject the second fuel to the cylinder. Specifically, when the vehicle is in a rapid acceleration state, for any cylinder, after the first fuel injection device injects the first fuel into the cylinder, the required amount of the second fuel, that is, the third required amount, may be recalculated according to the amount of the first fuel actually injected into the cylinder, and then the required amount of the second fuel calculated in step 110, that is, the second required amount, may be adjusted; when the first fuel quantity actually injected into the cylinder is smaller than the first demand quantity, the total fuel quantity in each cylinder can be adjusted by increasing the injection quantity of the second fuel, and further the problem of insufficient power caused by too little fuel in the cylinder due to injection delay of the first fuel in a vehicle rapid acceleration state is solved.
Based on the above scheme, optionally, the engine comprises six cylinders, and the first position before the top dead center is 138 degrees before the top dead center, and the second position before the top dead center is 78 degrees before the top dead center.
Specifically, for an engine including 6 cylinders, for each cylinder, the first fuel and the second fuel are not injected into the cylinder 138 degrees before top dead center; at 78 degrees before top dead center, the first fuel injection was completed in the cylinder and the second fuel was not injected. And, for a 6 cylinder engine, calculating the demand amounts of the first fuel and the second fuel at 138 degrees before top dead center, and then controlling the first fuel injection device to inject the first fuel into the cylinder according to the calculated first fuel demand amount; and recalculating the demand amount of the second fuel 78 degrees before top dead center, and controlling the second fuel injection device to inject the second fuel into the cylinder according to the recalculated demand amount of the second fuel, so that the first fuel and the second fuel injected into the cylinder can be ensured to be fully combusted, the emission performance of the engine is improved, and the first fuel and the second fuel injected into each cylinder are ensured not to be too much, so that the engine has good economic performance.
Optionally, the first fuel is methanol and the second fuel is diesel.
The invention provides a method for controlling the proportion of dual fuels of an engine, which comprises the steps of calculating a first demand quantity of a first fuel and a second demand quantity of a second fuel at a first position before the top dead center of each cylinder when a first fuel injection device and a second fuel injection device do not inject the first fuel and the second fuel to the cylinder when the engine is judged to be in a rapid acceleration state, and controlling the first fuel injection device to inject the first fuel to the cylinder according to the first fuel demand quantity; and calculating a third required amount of the second fuel at a second position before top dead center of each cylinder where the second fuel is not injected into the cylinder by the second fuel injection means after injection of the first fuel into the cylinder by the first fuel injection means is completed, and updating the second required amount with the third required amount, and then controls the second fuel injection means to inject the second fuel to each cylinder in accordance with the third required amount, therefore, when the vehicle is in a rapid acceleration working condition, after the first fuel injection of each cylinder is finished, the injection amount of the second fuel is adjusted in accordance with the amount of the first fuel actually injected into the cylinder, so that when there is a delay in the injection of the first fuel and the amount of the first fuel actually injected into the cylinder is too small, the proportion of two fuels entering an engine cylinder is controlled by increasing the injection quantity of the second fuel, so that the problem of insufficient vehicle power caused by less fuel entering the cylinder due to the injection delay of methanol under the condition of sudden acceleration of the vehicle is avoided.
Example two
Fig. 2 is a flowchart of an engine dual-fuel ratio control method according to a second embodiment of the present invention, and the present embodiment is based on the first embodiment and further provides an optional engine dual-fuel ratio control method.
Optionally, before determining that the engine is in the rapid acceleration state, the method includes:
and 102, judging the working condition of the engine according to at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the torque oil demand of the engine.
Specifically, according to the correlation between the engine speed change rate, the accelerator pedal opening change rate, and the engine torque change demand oil amount change rate, when the accelerator pedal opening change rate becomes large, the engine speed change rate and the engine torque demand oil amount change rate also become large. Under the condition that an engine system has no fault, the working condition of the engine can be judged by detecting at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the oil quantity required by the torque of the engine. Optionally, the engine operating conditions include a rapid acceleration operating condition, a rapid deceleration operating condition, and a steady state operating condition.
Optionally, the engine operating condition is judged according to at least one of the engine speed change rate, the accelerator pedal opening change rate and the engine torque demand oil quantity change rate, and the judgment comprises the following steps:
and when the engine speed change rate is greater than a first speed change rate threshold value, or the accelerator pedal opening change rate is greater than a first accelerator opening change rate threshold value, or the engine torque demand oil quantity change rate is greater than a first demand oil quantity change rate threshold value, judging that the engine is in a rapid acceleration state.
Specifically, a first rotation speed change rate threshold, a first throttle opening change rate threshold, and a first required oil amount change rate threshold may be preset, where the first rotation speed change rate threshold may be a minimum rotation speed change rate corresponding to a rapid acceleration of the vehicle obtained through a large number of experiments, the first throttle opening change rate threshold may be a minimum throttle opening change rate corresponding to a rapid acceleration of the vehicle obtained through a large number of experiments, and the first required oil amount change rate threshold may be a minimum engine torque required oil amount change rate corresponding to a rapid acceleration of the vehicle obtained through a large number of experiments.
Optionally, determining the engine operating condition according to at least one of the engine speed change rate, the accelerator pedal opening change rate, and the engine torque demand oil volume change rate further includes:
when the engine speed change rate is smaller than or equal to a second speed change rate threshold value, or the accelerator pedal opening change rate is smaller than or equal to a second accelerator opening change rate threshold value, or the engine torque demand oil quantity change rate is smaller than or equal to a second demand oil quantity change rate threshold value, the engine is judged to be in a rapid deceleration state; the engine dual-fuel proportion control method further comprises the following steps:
and step 130, if the engine is judged to be in the rapid deceleration state, controlling the first fuel injection device to stop injecting the first fuel, wherein the second fuel demand of each cylinder is equal to the total fuel demand of the cylinder.
Specifically, a second rotation speed change rate threshold, a second throttle opening change rate threshold, and a second required oil amount change rate threshold may be preset, where the second rotation speed change rate threshold may be a maximum rotation speed change rate corresponding to a vehicle that is obtained after a large number of experiments during rapid deceleration, the second throttle opening change rate threshold may be a maximum throttle opening change rate corresponding to a vehicle that is obtained after a large number of experiments during rapid acceleration, and the second required oil amount change rate threshold may be a maximum engine torque required oil amount change rate corresponding to a vehicle that is obtained after a large number of experiments during rapid acceleration.
Specifically, for fuel with methanol and long cylinder path, when the vehicle is in a rapid deceleration state, fuel may remain in the delivery path, for example, in the intake manifold for methanol, which may cause excessive fuel entering the cylinder and excessive in-cylinder pressure, resulting in fuel not being combusted, and even causing damage to the engine. Based on the problem, the embodiment provides the method, when the engine is determined to be in the rapid deceleration state, the first fuel injection device is controlled to stop injecting the first fuel, and the second fuel injection device is controlled to inject the second fuel into each cylinder according to the calculated total demand of fuel for each cylinder, so that the problems that when the vehicle is in the rapid deceleration state, the first fuel injected into the cylinder is too much due to the injection lag of the first fuel, the pressure in the cylinder is too high, the fuel combustion is insufficient, the economy and the emission performance of the engine are influenced, and even the engine is damaged are avoided.
Optionally, when the engine speed change rate is greater than a second speed change rate threshold and less than or equal to a first speed change rate threshold, or the accelerator pedal opening change rate is greater than a second accelerator opening change rate threshold and less than or equal to a first accelerator opening change rate threshold, or the engine torque demand oil quantity change rate is greater than a second demand oil quantity change rate threshold and less than or equal to a first demand oil quantity change rate threshold, determining that the engine is in a steady-state working condition; the engine dual-fuel proportion control method further comprises the following steps:
and step 140, when the engine is in a steady-state working condition, controlling the first fuel injection device to inject the first fuel to each cylinder according to the first demand quantity of the first fuel, and controlling the second fuel injection device to inject the second fuel to each cylinder according to the second demand quantity of the second fuel.
Specifically, when the engine is in a steady-state working condition, the change rate of the throttle opening is basically unchanged or slightly changed, correspondingly, the change rate of the engine speed is basically unchanged or slightly changed, and the change rate of the engine torque required oil quantity is basically unchanged or slightly changed, the required quantity of the first fuel and the required quantity of the second fuel corresponding to each cylinder are basically not changed suddenly, and the problem of certain fuel injection delay cannot occur, so that the first fuel injection device is controlled to inject the first fuel to the corresponding cylinder according to the first required quantity of the first fuel calculated at the first position before the top dead center, and the second fuel injection device is controlled to inject the second fuel to the corresponding cylinder according to the second required quantity of the second fuel calculated at the first position before the top dead center.
Optionally, in step 120, calculating a third demand for the second fuel at a second position before top dead center of each cylinder includes:
calculating the total demand of the second fuel of each cylinder in real time according to the engine torque at the second position before the top dead center of the cylinder;
equivalently converting a first fuel actually injected into the cylinder by the first fuel injection means into a second fuel amount in accordance with a calorific value;
and determining the difference between the total required quantity of the second fuel of the cylinder and the quantity of the second fuel obtained by the equivalent conversion of the first fuel as a third required quantity of the second fuel of the cylinder.
Specifically, when the engine is in a rapid acceleration state, the second fuel amount injected into the cylinder by the second fuel injection device is controlled according to the first fuel amount actually injected into the cylinder. And calculating the total demand of the second fuel of each cylinder according to the engine torque at a second position before the top dead center of each cylinder in one cycle period of work doing of each cylinder cycle, wherein the total demand can be the total demand of the second fuel when the engine only uses the second fuel. Because a certain amount of first fuel is injected into the cylinder when the first fuel is injected at the second position before the top dead center of the cylinder, in order to calculate the third demand of the second fuel according to the first fuel amount actually injected into the cylinder, the first fuel actually injected into the cylinder can be equivalently converted into the second fuel amount according to the calorific value, and finally the difference value between the total demand of the second fuel and the second fuel amount obtained by the equivalent conversion of the first fuel is determined as the third demand of the second fuel of the cylinder, so that the demand of the second fuel is adjusted according to the first fuel actually injected into the cylinder when the engine is in a rapid acceleration state, and the problem of power shortage caused by less fuel in the cylinder due to the fact that the path of the first fuel is long and the fuel is injected lagged when the engine is in the rapid acceleration state can not occur.
The method for controlling the dual-fuel ratio of the engine provided by the embodiment detects at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the fuel quantity required by the torque of the engine in real time, judging the working condition of the engine according to at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the oil quantity required by the torque of the engine, and controls the first fuel injection device to stop injecting the first fuel when the engine is determined to be in the rapid deceleration state, the second fuel demand of each cylinder is equal to the total fuel demand of the cylinder, so that the condition that the vehicle is in the rapid deceleration state is avoided, excessive injection of the first fuel into the cylinder leads to excessive in-cylinder pressure due to the hysteresis of the injection of the first fuel, so that the fuel combustion is insufficient, the economical efficiency and the emission performance of the engine are influenced, and even the engine is damaged.
EXAMPLE III
Fig. 3 is a schematic structural diagram of a dual-fuel proportional control device of an engine according to a third embodiment of the present invention, where the control device can execute the dual-fuel proportional control method of the engine according to any embodiment of the present invention, the engine includes a first fuel injection device, a second fuel injection device, and a plurality of cylinders that sequentially cycle to do work according to a set sequence, and the dual-fuel proportional control device of the engine includes:
the first calculation control module 210 is used for calculating a first demand quantity of a first fuel and a second demand quantity of a second fuel at a first position before the top dead center of each cylinder if the engine is in a rapid acceleration state, and controlling a first fuel injection device to inject the first fuel to each cylinder according to the calculated first demand quantity;
an update control module 220 for calculating a third demand for the second fuel at a second position before top dead center of each cylinder, updating the second demand for the second fuel in accordance with the third demand, and controlling the second fuel injection device to inject the second fuel in accordance with the third demand into each cylinder;
wherein, for any cylinder, at the first position before top dead center, neither the first fuel injection means nor the second fuel injection means injects fuel into the cylinder; when the first fuel injection device finishes injecting the first fuel to the cylinder, the second fuel injection device does not inject the second fuel to the cylinder.
According to the engine dual-fuel proportion control device, when the engine is judged to be in a rapid acceleration state through the first calculation control module, the first demand quantity of the first fuel and the second demand quantity of the second fuel are calculated at the first position before the top dead center of each cylinder when the first fuel injection device and the second fuel injection device do not inject the first fuel and the second fuel to the cylinder, and the first fuel injection device is controlled to inject the first fuel to the cylinder according to the first fuel demand quantity; and calculating a third demand amount of the second fuel at a second position before top dead center of each cylinder where the first fuel injection device is injected into the cylinder, and the second fuel injection device is not injecting the second fuel into the cylinder, by the update control module, and updating the second demand amount with the third demand amount, and then controls the second fuel injection means to inject the second fuel to each cylinder in accordance with the third required amount, therefore, when the vehicle is in a rapid acceleration working condition, after the first fuel injection of each cylinder is finished, the injection amount of the second fuel is adjusted in accordance with the amount of the first fuel actually injected into the cylinder, so that when there is a delay in the injection of the first fuel and the amount of the first fuel actually injected into the cylinder is too small, the proportion of two fuels entering an engine cylinder is controlled by increasing the injection quantity of the second fuel, so that the problem of insufficient vehicle power caused by less fuel entering the cylinder due to the injection delay of methanol under the condition of sudden acceleration of the vehicle is avoided.
Example four
Fig. 4 is a schematic structural diagram of an engine dual-fuel proportional control device according to a fourth embodiment of the present invention, which is based on the third embodiment, and further provides an optional engine dual-fuel proportional control device.
Optionally, the engine dual-fuel proportional control device further includes an engine working condition determining module 230, where the engine working condition determining module 230 includes:
the detection unit 231 is used for detecting at least one of the change rate of the engine rotating speed, the change rate of the opening degree of an accelerator pedal and the change rate of the engine torque demand oil quantity in real time;
and the judging unit 232 is used for judging the working condition of the engine according to at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of the accelerator pedal and the change rate of the oil quantity required by the torque of the engine.
Optionally, the determining unit 232 includes a rapid acceleration state determining subunit 2321, configured to determine that the engine is in a rapid acceleration state when the engine speed change rate is greater than a first speed change rate threshold, or the accelerator pedal opening change rate is greater than a first accelerator opening change rate threshold, or the engine torque demand oil volume change rate is greater than a first demand oil volume change rate threshold.
Optionally, the determining unit 232 further includes a sudden deceleration state determining subunit 2322, configured to determine that the engine is in a sudden deceleration state when the engine speed change rate is less than or equal to a second speed change rate threshold, or the accelerator pedal opening change rate is less than or equal to a second accelerator opening change rate threshold, or the engine torque demand oil volume change rate is less than or equal to a second demand oil volume change rate threshold;
the engine dual fuel ratio control apparatus includes a second control module 240 for controlling the first fuel injection apparatus to stop injecting the first fuel if it is determined that the engine is in a rapid deceleration state, and the second fuel demand for each cylinder is equal to the total fuel demand for the cylinder.
Optionally, the determining unit 232 further includes a steady-state condition determining subunit 2323, configured to determine that the engine is in the steady-state condition when the engine speed change rate is greater than the second speed change rate threshold and is less than or equal to the first speed change rate threshold, or the accelerator pedal opening change rate is greater than the second accelerator pedal opening change rate threshold and is less than or equal to the first accelerator pedal opening change rate threshold, or the engine torque demand oil quantity change rate is greater than the second demand oil quantity change rate threshold and is less than or equal to the first demand oil quantity change rate threshold;
the engine dual fuel proportional control apparatus further includes a third control module 250 configured to control the first fuel injection apparatus to inject the first fuel to each cylinder according to a first demand amount of the first fuel and control the second fuel injection apparatus to inject the second fuel to each cylinder according to a second demand amount of the second fuel when the engine is in a steady state operating condition.
Optionally, the update control module includes a second total fuel demand calculation unit 221, an equivalent conversion unit 222, a third demand calculation unit 223;
the second fuel total demand calculation unit 221 is configured to calculate a total demand of the second fuel for each cylinder in real time according to the engine torque at a second position before the top dead center of the cylinder;
the equivalent conversion unit 222 is for converting the first fuel, which is actually injected into the cylinder by the first fuel injection means, into the second fuel amount in an equivalent manner in accordance with the calorific value;
the third demand calculation unit 223 is configured to determine the difference between the total demand of the second fuel for the cylinder and the amount of the second fuel equivalently converted from the first fuel as the third demand of the second fuel for the cylinder.
The engine dual-fuel proportion control device provided by the embodiment detects at least one of the change rate of the engine speed, the change rate of the accelerator pedal opening and the change rate of the engine torque demand oil quantity in real time through the detection unit of the engine working condition judgment module, judges the engine working condition according to at least one of the change rate of the engine speed, the change rate of the accelerator pedal opening and the change rate of the engine torque demand oil quantity, controls the first fuel injection device to stop injecting the first fuel through the second control module when the sudden deceleration state judgment subunit of the judgment unit judges that the engine is in a sudden deceleration state, and avoids the phenomenon that the cylinder internal pressure is overhigh due to the excessive first fuel injected in the cylinder caused by the injection lag of the first fuel when the vehicle is in the sudden deceleration state, so that the fuel combustion is insufficient, the economical efficiency and the emission performance of the engine are influenced, and even the engine is damaged.
The device can execute the method provided by any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the execution method.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (15)
1. A dual-fuel proportion control method for an engine is characterized in that the engine comprises a first fuel injection device, a second fuel injection device and a plurality of cylinders which circularly work in sequence according to a set sequence, and the dual-fuel proportion control method for the engine comprises the following steps:
if the engine is in a rapid acceleration state, calculating a first demand quantity of the first fuel and a second demand quantity of the second fuel at a first position before the top dead center of each cylinder, and controlling a first fuel injection device to inject the first fuel to each cylinder according to the calculated first demand quantity;
calculating a third demand amount of the second fuel at a second position before top dead center of each of the cylinders, updating the second demand amount of the second fuel in accordance with the third demand amount, and controlling a second fuel injection device to inject the second fuel in accordance with the third demand amount into each of the cylinders;
wherein, for any of the cylinders, at a first position before the top dead center, neither the first fuel injection means nor the second fuel injection means injects fuel into the cylinder; when the second position is reached, the first fuel injection device finishes injecting the first fuel into the cylinder, and the second fuel injection device does not inject the second fuel into the cylinder.
2. The engine dual fuel ratio control method of claim 1, before determining that the engine is in a hard acceleration state, comprising:
detecting at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the oil quantity required by the torque of the engine in real time;
and judging the working condition of the engine according to at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of the accelerator pedal and the change rate of the oil quantity required by the torque of the engine.
3. The engine dual fuel ratio control method as claimed in claim 2, characterized in that the engine is determined to be in the hard acceleration state when the engine speed change rate is greater than a first speed change rate threshold, or the accelerator pedal opening change rate is greater than a first accelerator opening change rate threshold, or the engine torque demand fuel amount change rate is greater than a first demand fuel amount change rate threshold.
4. The engine dual fuel ratio control method as claimed in claim 3, characterized in that the engine is determined to be in a rapid deceleration state when the engine speed change rate is less than or equal to a second speed change rate threshold, or the accelerator pedal opening change rate is less than or equal to a second accelerator opening change rate threshold, or the engine torque oil demand change rate is less than or equal to a second oil demand change rate threshold; the engine dual-fuel proportion control method further comprises the following steps:
and if the engine is determined to be in a rapid deceleration state, controlling the first fuel injection device to stop injecting the first fuel, wherein the second fuel demand of each cylinder is equal to the total fuel demand of the cylinder.
5. The engine dual fuel ratio control method as claimed in claim 4, characterized in that the engine is determined to be in a steady state condition when the engine speed change rate is greater than the second speed change rate threshold and less than or equal to a first speed change rate threshold, or the accelerator pedal opening change rate is greater than the second accelerator opening change rate threshold and less than or equal to the first accelerator opening change rate threshold, or the engine torque demand fuel amount change rate is greater than a second demand fuel amount change rate threshold and less than or equal to a first demand fuel amount change rate threshold;
the engine dual-fuel proportion control method further comprises the following steps: and when the engine is in a steady-state working condition, controlling the first fuel injection device to inject the first fuel to each cylinder according to the first demand quantity of the first fuel, and controlling the second fuel injection device to inject the second fuel to each cylinder according to the second demand quantity of the second fuel.
6. The engine dual fuel ratio control method as claimed in claim 2, wherein said calculating a third demand for the second fuel at a second position before top dead center of each of the cylinders comprises:
calculating the total demand of the second fuel of each cylinder in real time according to the engine torque at the second position before the top dead center of the cylinder;
equivalently converting the first fuel actually injected into the cylinder by the first fuel injection means into the second fuel amount in accordance with the calorific value;
and determining the difference between the total required quantity of the second fuel of the cylinder and the quantity of the second fuel obtained by the equivalent conversion of the first fuel as a third required quantity of the second fuel of the cylinder.
7. The engine dual fuel ratio control method of claim 1 wherein the engine includes six of the cylinders, the first position before top dead center being 138 degrees before top dead center, the second position before top dead center being 78 degrees before top dead center.
8. The engine dual fuel ratio control method of claim 1, wherein the first fuel is methanol and the second fuel is diesel.
9. A dual-fuel proportional control device of an engine is characterized in that the engine comprises a first fuel injection device, a second fuel injection device and a plurality of cylinders which circularly work in sequence according to a set sequence, and the dual-fuel proportional control device of the engine comprises:
the first calculation control module is used for calculating a first demand of the first fuel and a second demand of the second fuel at a first position before the top dead center of each cylinder if the engine is in a rapid acceleration state, and controlling a first fuel injection device to inject the first fuel to each cylinder according to the calculated first demand;
an update control module for calculating a third demand amount of the second fuel at a second position before top dead center of each of the cylinders, updating the second demand amount of the second fuel according to the third demand amount, and controlling a second fuel injection device to inject the second fuel to each of the cylinders according to the third demand amount;
wherein, for any of the cylinders, at a first position before the top dead center, neither the first fuel injection means nor the second fuel injection means injects fuel into the cylinder; when the second position is reached, the first fuel injection device finishes injecting the first fuel into the cylinder, and the second fuel injection device does not inject the second fuel into the cylinder.
10. The engine dual fuel proportion control device of claim 9, further comprising an engine operating condition determining module, the engine operating condition determining module comprising:
the detection unit is used for detecting at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of an accelerator pedal and the change rate of the torque required oil quantity of the engine in real time;
and the judging unit is used for judging the working condition of the engine according to at least one of the change rate of the rotating speed of the engine, the change rate of the opening degree of the accelerator pedal and the change rate of the oil quantity required by the torque of the engine.
11. The dual fuel ratio control device for the engine as claimed in claim 10, wherein the determining unit comprises a rapid acceleration state determining subunit configured to determine that the engine is in the rapid acceleration state when the engine speed change rate is greater than a first speed change rate threshold, or the accelerator pedal opening change rate is greater than a first accelerator opening change rate threshold, or the engine torque demand fuel amount change rate is greater than a first demand fuel amount change rate threshold.
12. The dual fuel ratio control device for the engine as claimed in claim 11, wherein the determining unit further comprises a rapid deceleration state determining sub-unit for determining that the engine is in a rapid deceleration state when the engine speed change rate is less than or equal to a second speed change rate threshold, or the accelerator pedal opening change rate is less than or equal to a second accelerator opening change rate threshold, or the engine torque demand fuel amount change rate is less than or equal to a second demand fuel amount change rate threshold;
the engine dual-fuel proportional control device comprises a second control module and a second control module, wherein the second control module is used for controlling the first fuel injection device to stop injecting the first fuel if the engine is determined to be in a rapid deceleration state, and the second fuel demand of each cylinder is equal to the total fuel demand of the cylinder.
13. The engine dual-fuel ratio control device as claimed in claim 12, wherein the determining unit further comprises a steady-state condition determining subunit, configured to determine that the engine is in a steady-state condition when the engine speed change rate is greater than the second speed change rate threshold and less than or equal to a first speed change rate threshold, or the accelerator pedal opening change rate is greater than the second accelerator opening change rate threshold and less than or equal to the first accelerator opening change rate threshold, or the engine torque required oil amount change rate is greater than a second required oil amount change rate threshold and less than or equal to a first required oil amount change rate threshold;
the engine dual-fuel proportion control device further comprises a third control module, and the third control module is used for controlling the first fuel injection device to inject the first fuel to each cylinder according to the first demand quantity of the first fuel and controlling the second fuel injection device to inject the second fuel to each cylinder according to the second demand quantity of the second fuel when the engine is in a steady-state working condition.
14. The engine dual fuel ratio control device of claim 10, wherein the update control module comprises a second total fuel demand calculation unit, an equivalent conversion unit, a third demand calculation unit;
the second fuel total demand calculation unit is used for calculating the total demand of the second fuel of each cylinder in real time according to the engine torque at a second position before the top dead center of the cylinder;
the equivalent conversion unit is used for equivalently converting the first fuel actually injected into the cylinder by the first fuel injection device into a second fuel quantity according to a heat value;
the third demand calculation unit is configured to determine a difference between a total demand of the second fuel for the cylinder and the amount of the second fuel equivalently converted from the first fuel as a third demand of the second fuel for the cylinder.
15. An automobile comprising an engine and an electronic engine control unit, said electronic engine control unit having integrated therein said dual fuel ratio engine control device as provided in any one of claims 9-14.
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| JPH0458051A (en) * | 1990-06-28 | 1992-02-25 | Suzuki Motor Corp | Used fuel determining device for internal combustion engine |
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| CN104595049A (en) * | 2014-11-27 | 2015-05-06 | 长城汽车股份有限公司 | Dual fuel engine transient torque compensation system, compensation method and vehicle |
| CN106150733A (en) * | 2015-03-27 | 2016-11-23 | 长城汽车股份有限公司 | The control method of dual fuel engine, device and the automobile with this device |
| CN107620646A (en) * | 2017-08-10 | 2018-01-23 | 北汽福田汽车股份有限公司 | Dual-purpose fuel vehicle and control method for dual-purpose fuel vehicle, device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH0458051A (en) * | 1990-06-28 | 1992-02-25 | Suzuki Motor Corp | Used fuel determining device for internal combustion engine |
| CN102072036A (en) * | 2011-01-17 | 2011-05-25 | 吕国怀 | Method and device for controlling fuel-gas ratio of dual-fuel engine |
| CN104595049A (en) * | 2014-11-27 | 2015-05-06 | 长城汽车股份有限公司 | Dual fuel engine transient torque compensation system, compensation method and vehicle |
| CN106150733A (en) * | 2015-03-27 | 2016-11-23 | 长城汽车股份有限公司 | The control method of dual fuel engine, device and the automobile with this device |
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